Process of alloying metals with lead



Patented Nov. 29, 1938 UNITED STATES PATENT. OFFICE rnoonss or ALLOYING METALS WITH No Drawing.

Application July 22, 1937, Serial No. 155,120. In Great Britain August 8, 1936 17 Claims.

In my United States application Serial No. 115,629, filed December 12th, 1936, which has issued as Patent 2,097,560 dated Nov. 2, 1937, I have described a method of preparing alloys of lead by adding to a bath of a molten alloy of lead and tin a lead halide flux containing a reducible compound (e. g. an oxide) of the metal to be alloyed with the lead. Under these conditions the tin replaces the metal present in the reducible compound, tin oxide separating with the flux and the other metal replacing tin in the bath. One important advantage of using a lead halide flux is that the operation may be carried out at a low temperature of the order of 450- I now flnd that this method is of more general application, and the present invention provides a method of alloying a metal A with lead, which consists in acting upon a bath of molten lead containing a metal B with a flux containing a lead halide and an oxide of the metal A, the metal B being one which, under these conditions, will interact with the oxide and replace the metal A, which will enter the bath of molten lead.

The lead halides form low melting point mixtures with metallic oxides, and enable the reac tion to be carried out at a low temperature of the order of 450-550 C.

The metal B may be either lead, or some metal other than tin alloyed with lead. Replacement of tin is excluded from the present invention, since it is already claimed in my application Serial No. 115,629 aforesaid.

I have found that copper, selenium, silver, tellurium and bismuth can be caused to replace lead or other metals in the bath by incorporating them as oxides in the flux. They cannot, however, be removed from the bath by the method herein described.

Lithium, sodium, magnesium, aluminium, potassium, calcium, zinc and strontium can readily be replaced in the bath by treatment with a flux containing a suitable metallic oxide. They cannot, however, be introduced into the bath by incorporating them in the flux as oxides.

In the case of nickel, cadmium, arsenic and antimony, the reaction is reversible and these metals can be extracted from or introduced into the bath.

The method has the advantage that pure oxides need not be employed, but ores, residues, chemical bye-products etc. may be used. Thus, for example, an antimony oxide ore may be mixed with the flux, the antimony passing directly into the lead, and being replaced by a metal B present in the bath.

When oxide residues are employed which con- 1 tain metallic particles, these in contact with the fluid flux melt and joint the metal bath.

Some examples of how the invention can be carried into effect will now be given.

In each of the examples quoted below the lead alloy is melted in a kettle and heated to about 550 C. The flux with the whole or a part of the metal oxide A is then added and the whole forms a fluid layer on top of the metal. Stirring is then commenced and is effected by the usual means until the reaction is finished, the balance, if any, of the metal oxide A being meanwhile added. In some cases it is preferable to make more than one flux addition and this is specially so where selective removal of a certain metal from the bath is aimed at.

In certain circumstances where it is desired that the reaction be carried out to a definite degree, such as in the preferential removal of a certain metal, it may be an advantage to work in a non-oxidizing atmosphere thus enabling the amount of oxygen taking part in the reaction to be controlled by the quantity of metal oxide added.

5 parts of silver oxide were mixed with 50 parts of lead fluoride and stirred into 1000 parts' of molten lead for fifteen minutes. The metal upon analysis contained 46% of the silver added as oxide, lead oxide replacing the reduced silver oxide in the flux. Similar results were obtained using lead chloride as a flux.

III

5 parts of tellurium oxide were treated in a manner similar to the above and of the tellurium added as crude replaced lead in the bath using a lead fluoride flux.

III

5 parts of bismuth oxide, 50 parts of lead fluoride and 1000 parts of molten lead were stirred for fifteen minutes, when 99% of the contained bismuth replaced lead in the metal bath.

5 parts of nickel oxide, 50 parts of lead fluoride and 1000 parts of molten lead were stirred together for fifteen minutes after which 10% of the nickel added was found to be the lead.

Using lad fluoride as a flux 1000 parts of molten lead were stirred for fifteen minutes with 100 parts of lead fluoride and 200 parts of antimony oxide after which of the antimony was found to have alloyed with the metal.

VII

5 parts of cuprous oxide, 50 parts lead fluoride and 1000 parts of molten lead werestirred together for fifteen minutes after which it was found that 72% of the copper added as oxide was alloyed with the bath.

VIII

5 parts of selenium oxide, 50 parts of lead fluoride and 1000 parts of molten lead were stirred for fifteen minutes after which it was found that 16% of the selenium added as oxide had replaced lead and become alloyed in the bath.

75 parts of arsenious oxide, 150 parts of lead chloride and 1000 parts of molten lead containing 5% of antimony were stirred for fifteen minutes. In this example arsenic replaced both lead and antimony in the bath, which was found on final analysis to contain 4.4% of antimony and 2.86% of arsenic.

Although in .the foregoing examples the oxides of metals A are quoted it must be understood that the process is not confined to the primary addition of the oxides of metal A as such. Thus oxides of metal A may be formed in situ by a variety of methods, e. g., carbonates or nitrates decomposable by heating provide a ready source of oxides, compounds or mixtures of lead oxide with other metallic oxides, e. g., lead antimoniate act similarly. Also processes of double decomposition are applicable, e. g., a mixture of silver chloride and lead oxide heated together on a bath of molten lead give rise to silver oxide and lead chloride, the silver oxide being then available to act as the oxide of metal A. Their application, by the method according to the invention, to the manufacture of lead alloys provides a useful method for the treatment of residues, chemical bye-products etc. as previously mentioned.

In the case of the lead fluoride metal oxide fluxes, these may, after removal from the bath, he smelted direct with carbon and lime, the fluorine passing into the slag as calcium fluoride.

Alternatively, the flux may be mixed with a proportion of carbon sumcient only to reduce a part of the metal oxides and the residual fiux now enriched in lead fluoride can be used again.

In the case of lead chloride metal oxide fluxes, the lead chloride can be separated by volitilization from the metal oxide, or by leaching with water.

What I claim as my invention and desire to secure by Letters Patent is:

1. A process of alloying metals with lead, which comprises the steps of treating a bath of molten lead with a flux, consisting of a mixture of a lead halide and an oxide of a metal having, under the alloyed with conditions of the process, a less affinity for oxygen than lead, thereby effecting oxidation of a portion of the lead and replacement thereof in the bath by the said metal and removing the lead oxide so formed by separating the flux from the bath.

2. A process of alloying copper with lead, which comprises the steps of treating a bath of molten lead with a flux, consisting of a mixture of a lead halide and copper oxide, thereby effecting oxidation of a portion of the lead and replacement thereof in the bath by copper, and removing the lead oxide so formed by separating the flux from the bath.

3. A process of alloying tellurium with lead, which comprises the steps of treating a bath of molten lead with a flux, consisting of a mixture of a lead halide and tellurium oxide, thereby effecting oxidation of a portion of the lead and replacement thereof in the bath by tellurium, and removing the lead oxide so formed by separating 1 the flux from the bath.

4. A process of alloying silver with lead, which comprises the steps of treating a bath of molten lead with a flux, consisting of a mixture of a lead halide and silver oxide, thereby effecting oxidation of a portion of the lead and replacement thereof in the bath by silver, and removing the lead oxide so formed by separating the flux from the bath.

5. A process according to claim 1, in which the reaction is carried out in a non-oxidizing atmosphere.

6. A process according to claim 1, in which the oxide of the metal to be alloyed with the lead is formed in situ.

'7. A process according to claim 1, in which the metal oxide is introduced into the flux in the form of an ore or residue.

8. A process of alloying metals with lead, which comprises the steps of treating a bath of molten lead with a flux, consisting of a mixture of a lead chloride and an oxide of a metal having, under the conditions of the process, a less aflinity for oxygen than lead, thereby effecting oxidation of a portion of the lead and replacement thereof in the bath by the said metal and removing the lead oxide so formed by separating the flux from the bath.

9. A process of alloying metals with lead, which comprises the steps of treating a bath of molten lead with a flux, consisting of a mixture of a lead fluoride and an oxide of a metal having, under the conditions of the process, a less afllnity for oxygen than lead, thereby effecting oxidation of a portion of the lead and replacement thereof in the bath by the said metal and removing the lead oxide so formed by separating the flux from the bath. V

10. A process of alloying metals with lead, which comprises the steps of treating a bath of a molten lead alloy with a flux, consisting of a mixture of a lead halide and an oxide of a metal having, under the conditions of the process, a less aflinity for oxygen than a metal other than tin in the bath, thereby effecting oxidation of said metal in the bath and its replacement by the metal obtained by the reduction of the oxide in the flux and separating the flux from the bath.

11. A process of alloying arsenic with lead, which comprises the steps of treating a bath of a molten lead-antimony alloy with a flux consisting of a mixture of a lead halide and arsenious ox-- r ide, thereby efiecting oxidation of a portion of the lead and antimony, and replacement thereof 15 in the bath by arsenic, and removing the lead om'de and antimony oxide so formed by separating the flux from the bath.

12. A process according to claim 10, in which the reaction is carried out in a non-oxidizing atmosphere.

13. A process according to claim 10, in which the oxide of the metal to be alloyed with the lead is formed in situ.

14. A process according to claim 10, in which the metal oxide is introduced into the flux in the form of an ore or residue.

15. A process of alloying metals with lead, which comprises the steps of treating a oath of a molten lead alloy with a flux, consisting of a mixture of a lead halide and an oxide of a metal having, under the conditions of the process, a less afiinity for oxygen than a metal other than tin in the bath, thereby effecting om'dation of said metal in the bath and its replacement by the metal obtained by the reduction of the oxide in the flux, separating the flux from the bath, and treating the flux with a quantity of carbon snfiicient to reduce a part only of the metallic oxides therein, so rendering the flux suitable forre-use.

16. A process of alloying metals with lead, which comprises the steps of treating a bath of a molten lead alloy with a flux, consisting of a mixture of a lead halide and an oxide of a metal having, under the conditions of the process, a less afilnity for oxygen than a metal other than tin in the bath, thereby effecting oxidation of said metal in the bath and its replacement by the metal obtained by the reduction of the oxide in the flux, separating the flux from the bath, and smelting the flux direct to reduce the oxides therein to metal.

17. A process of recovering metal particles from oxide residues, which consistsin treating a bath containing molten lead with a flux containing the residue and a lead halide, thereby efiecting union between the metal particles and the ba h, 20

and thereafter separating the flux from the bath. 

